Let's cover the basics we've learned over time.
1. Boot to safe mode.
b. try again in SAFE MODE.
2. Look up other defrraggers like defraggler.
3. Ignore it. It rarely speeds up the system and if there is hardware issues can corrupt what's on the drive.
Again, you are traveling down a very well beaten path.
I installed XP PRO on 40GB Drive. I then decided to dual boot with Linux. XP is now on 18.3 GB NTFS partition. I then upgraded to service pac 3 and latest updates as of yesterday. There are very little I have done in XP, but I only have 7.57 GB free space. The original drive was only 6GB, so I figure XP should only take up about 3 GB of disk space. I tried defragging, but get message - can not defrag. Is there a third party app that can defrag the drive? What to do?